Acidosis in ruminants is normally caused by a feed overload. This occurs, for example, because of a feed error (e.g. too much grain because of accidentally feeding a finish ration instead of a normal ration) or because of a feed breakdown (e.g. because the weather or other cause prevents the animals from eating) followed by overeating. When the feed overload occurs, the bacteria in the rumen have not had a chance to adapt to the temporary situation and produce an excess of lactic acid. The harmful results that occur include the death of rumen bacteria and passage of lactic acid through the rumen wall into the bloodstream to lower the systemic pH. The death of rumen bacteria results in interference with the animal's digestion. The lowering of systemic pH can inhibit nervous system function and muscle response and can result in death.
According to the Merck Veterinary Manual (4th edition), one preferred treatment of acidosis involves emptying the rumen contents and replacing such with rumen contents from a healthy animal, and an alternative treatment involves emptying the rumen contents, irrigating the rumen 15 to 20 times and using balanced electrolytes to correct acid-base imbalance and dehydration and to restore renal function. These treatments are impractical especially if a plurality of animals are affected. Other treatments disclosed in Merck consist of oral drenching with calcium carbonate or magnesium hydroxide solutions. These treatments are not very effective and can lead to bloat.
Sodium bicarbonate has been used in the treatment of rumen acidosis. However, such use presents difficulties. For example, if an aqueous solution of sodium bicarbonate is pumped into an acidotic animal's rumen, large quantities of carbon dioxide quickly form and the animal has difficulty eructating these because of reduced muscle response; this leads to bloat and the risk of pressure on the animal's heart and death.
Dunn, B. H., Emerick, R. J. and Embry, L. B., Journal of Animal Science 48, No. 4 (1979) report some success in preventing acidosis in feed overload situations by including in the feed sodium bentonite and/or sodium bicarbonate. This is not a satisfactory solution because continued feeding does not result in continued weight gain improvement and because a higher incidence of urinary calculi was noted in lambs and steers on a continuing diet (maintenance doses) including sodium bicarbonate.